The effect of increasing amount of glucogenic precursors on reproductive performance in young postpartum range cows1

Abstract

Supplementing CP and propionate salts (PS) may improve economic returns in young range beef cows by increasing the dietary supply of glucogenic precursors. A 3-yr study conducted at Corona Range and Livestock Research Center (Corona, NM) from February to mid-July in 2005 (n = 80), 2006 (n = 81), and 2007 (n = 80) evaluated days to first estrus, calf weaning weight, BW change, and metabolic responses in 2- and 3-yr-old postpartum cows grazing native range. Cows were individually fed one of three 36% CP supplement treatments after parturition, with increasing glucogenic potential (GP) supplied by RUP and PS. Supplements were isoenergetic and fed at a rate of 908 g/cow per day twice weekly. Supplementation was initiated 7 d after calving and continued for an average of 95 d. Supplement treatments provided 1) 328 g of CP, 110 g of RUP and 0 g of PS (PS0); 2) 328 g of CP, 157 g of RUP, and 40 g of PS (PS40); or 3) 329 g of CP, 158 g of RUP, and 80 g of PS (PS80). Ultimately, PS0, PS40, and PS80 provided 44, 93, and 124 g of GP, respectively. Body weight was recorded weekly and serum was collected twice weekly for progesterone analysis to estimate days to first estrus. Cows were exposed to bulls for 60 d or less beginning in mid-May. Days to first estrus exhibited a quadratic (P = 0.06) response to GP resulting from the fewest days to first estrus with the consumption of PS40. Pregnancy rates were 88, 96, and 94% for cows fed PS0, PS40, and PS80, respectively (P = 0.11). Total kilograms of calf weaned per cow exposed to bulls for the supplementation and following year increased quadratically (P = 0.09). However, supplement did not affect milk composition or yield (P ≥ 0.53). Serum acetate half-life decreased linearly (P = 0.08) with increasing GP in 2007. Predicted margins were the greatest (quadratic; P = 0.03) for cows fed PS40. Even though supplement costs were greater for PS40 and PS80, cows fed PS40 had increased profits ($33.47/cow) compared with cows fed PS0 and PS80. This study implies that young postpartum cows fed additional glucogenic precursors may have improved reproductive efficiency and may wean more calf weight per cow exposed to breeding.

Supplementation with a mixture of whole rice bran and crude glycerin on metabolic responses and performance of primiparous beef cows

“…The nutrient supply of grasslands during the winter is insufficient to meet the requirements of the growing fetus in the last third of the pregnancy period, causing a negative energy balance that continues during early postpartum due to the demand for milk production (Bell, 1995;Astessiano et al, 2013). The negative energy balance is evidenced by a decrease in body condition score (BCS) and endocrine changes, such as an increase in non-esterified fatty acids (NEFA) and a decrease in glucose and insulin, which have a negative impact on follicle growth and ovulation (Wiltbank, 1970;Mulliniks et al, 2011).…”

BEEF SPECIES–RUMINANT NUTRITION CACTUS BEEF SYMPOSIUM: Sustainable and economically viable management options for cow/calf production through enhanced beef cow metabolic efficiency1

“…Although the level of milk production and insulin resistance has been primarily studied in dairy cows, increasing selection for milk production may increase insulin resistance and metabolic challenges for beef cows, especially young, growing 2-and 3-yr-old cows by partitioning nutrients away from growth and reproduction towards milk. Increasing insulin resistance and milk production will ultimately increase mobilization of body reserves and lower reproductive performance (Mulliniks et al, 2011). For instance, Hunter and Magner (1988) compared formaldehyde-treated casein-supplemented heifers with nonsupplemented heifers.…”

“…For example, Waterman et al (2007) reported as forage quality declines, tissues become less responsive to insulin, resulting in longer glucose half-life. In addition, enhanced energy metabolism in young range cows identified by faster glucose and acetate clearance rates has been reported to increase reproductive performance in beef cows (Waterman et al, 2006;Mulliniks et al, 2011). Therefore, during key physiological periods such as late gestation and early lactation when nutrient requirements increase and cattle are often grazing limited nutrients supplementation strategies could target improving energy utilization of both forage (i.e.…”

“…In addition, insulin resistance during early lactation in beef cows may inhibit protein synthesis and increase protein catabolism (Bell et al, 2000). Lactating, young range cows have been shown to be highly insulin resistant during early lactation, conducting a glucose tolerance test indicating glucose half-lives ranged 65 (Waterman et al, 2011) to 97 min (Mulliniks et al, 2011), which are up to 3 times greater than glucose half-lives in some high-producing dairy cows (Chagas et al, 2009;Lohrenz et al, 2010). The degree and extent of lean tissue mobilization during negative energy balance situations in response to grazing low-quality, extensive rangelands may need to be further investigated.…”

Protein and glucogenic precursor supplementation: A nutritional strategy to increase reproductive and economic output1

“…Data were compiled from 3 independent studies that spanned from 2000 to 2007 (Endecott et al, 2005;Waterman et al, 2006;Mulliniks, 2008;Mulliniks et al, 2011) but with similar designs. Data were compiled from 3 independent studies that spanned from 2000 to 2007 (Endecott et al, 2005;Waterman et al, 2006;Mulliniks, 2008;Mulliniks et al, 2011) but with similar designs.…”